Wellhead safety coupling and method of preventing leakage from a wellhead

ABSTRACT

A wellhead sealing apparatus and a method of preventing leakage from a wellhead while providing electrical conductors to the well are provided. The apparatus includes a housing that can be mounted to a wellhead and one or more electrical conductors which pass through the housing and are sealed to prevent leakage of fluids, for example, natural gas or methane, from the well head. One aspect of the invention includes a coupling assembly having a male or a female connector mounted in the housing and which is sealed with a hardenable fluid, for example, an adhesive, to minimize or prevent leakage from the housing. Aspects of the invention can be used to seal the electrical connections to wellheads containing harmful gases, such as methane or natural, gas, to minimize or prevent leakage of the gas.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from pending U.S. Provisional Patent Application 60/896,731, filed on Mar. 23, 2007, the disclosure of which is included by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention generally relates to methods and apparatus for providing at least one electrical conductor to a wellhead containing a fluid while preventing fluid leakage from the wellhead. More particularly, the present invention relates to methods and apparatus for providing electrical conductors to wellheads containing methane gas and preventing leakage of the methane gas.

2. Description of Related Art

Subsurface coal beds may often contain natural gas, for example, in the form of methane (CH₄). Typically, methane is produced during the natural conversion of organic material to coal. When the methane gas becomes trapped within a subsurface bed of coal, the trapped gas is commonly referred to as “coal bed methane.”

Just like any fossil fuel, the energy value of coal bed methane makes it desirable to extract the methane from the coal bed. (See Coal Bed Methane: Potential and Concerns, U.S. Geological Survey Fact Sheet FS 123-00, October 2000, incorporated by reference herein.) However, subsurface coal beds may also contain ground water, for example, ground water from naturally occurring aquifers. The presence of water in the methane containing coal bed makes it difficult to extract the methane in a cost effective fashion. Extracting methane from a water-containing coal bed typically requires pumping water from the subsurface coal bed to reduce the hydraulic pressure on the methane so the methane can escape from the coal bed. Since methane is less dense than air, once released, the methane will rise to the surface. However, controlling the extraction of water to optimize the extraction of methane is typically difficult.

Attempts to extract coal bed methane often include the use of submersible pumps used to limit the water level in the well so that more gas can be extracted. For example, reference is made to pending U.S. patent application Ser. No. 11/446,901 filed on Jun. 5, 2006 (the disclosure of which is incorporated by reference herein). However, to provide power to such pumps, electrical cables or wires are typically routed through the wellhead and down to the subsurface pump, which may be hundreds of feet down in the coal bed. However, this wiring to the pump is typically exposed to the high-pressure fluids, such as, methane and natural gas, in the well. In some instances, these pressurized fluids may pass through the insulating lining of the wires, for example, through a cut or pin hole in the insulation, or around the outside of the wires, for example, through the interstices between wires, and then pass the pressurized fluid all the way to the surface. If no precautions are taken at the wellhead, this pressurized gas can pass through the wellhead and expose personnel and equipment to noxious or flammable gases. In some instances, natural gas has passed from the wellhead through the wiring all the way the electronic equipment interface panel. This can result in exposure to dangerous gases, fires, or explosions at a distance from the wellhead, often to the confusion and bewilderment of personnel operating the wellhead.

Aspects of the present invention address or minimize this problem by minimizing or preventing the passage of pressurized fluids through the electrical wiring near the wellhead.

BRIEF SUMMARY OF ASPECTS OF THE INVENTION

One aspect of the invention is an electrical coupling assembly adapted to minimize or prevent the passage of fluids, for example, natural gas or methane, from the wires or cables on one side of the coupling assembly to the wires on the other side of the coupling assembly. Aspects of the invention include at least one male and at least one female connector having means for minimizing or preventing the passage of fluid from the wires connected to the male or female connector.

Another aspect of the invention is a method of providing at least one electrical conductor to a wellhead containing a fluid while preventing fluid leakage from the wellhead, the method including providing a cylindrical housing having a through hole, the housing adapted to be mounted to the wellhead; passing at least one electrical conductor through the hole of the cylindrical housing; and sealing the through hole and the at least one electrical conductor to substantially prevent the passage of the fluid through the housing. In one aspect, the housing is adapted to be mounted to the wellhead comprises a housing having an external thread engagable with the wellhead. In another aspect, passing at least one electrical conductor comprises passing at least one single, solid wire electrical conductor through the hole. In another aspect, sealing the through hole and the at least one electrical conductor comprises providing a hardenable fluid to the through hole and hardening the hardenable fluid to provide a substantially fluid-tight seal between an inside surface of the through hole and an outside surface of the at least one electrical conductor. In another aspect, passing at least one electrical conductor through the hole of the connector comprises passing at least one electrical conductor comprising an electrical coupling, for example, having a first male connector and a second female connector.

Another aspect of the invention is an apparatus for providing at least one electrical conductor to a wellhead containing a fluid while preventing fluid leakage from the wellhead. The apparatus may include a cylindrical housing having a through hole, the housing adapted to be mounted to the wellhead; at least one electrical conductor passing through the hole of the cylindrical housing; and means for sealing the through hole and the at least one electrical conductor to substantially prevent the passage of the fluid through the housing. In one aspect, the means for sealing the through hole and the at least one electrical conductor comprises a hardenable fluid adapted to provide a substantially fluid-tight seal between an inside surface of the through hole and an outside surface of the at least one electrical conductor when hardened, for example, an adhesive, such as, an epoxy or a silicone. In another aspect, the at least one electrical conductor comprises an electrical coupling, for example, a coupling having a first male connector and a second female connector.

A further aspect of the invention is an electrical coupling assembly adapted to provide at least one electrical conductor to a wellhead containing a fluid while preventing fluid leakage from the wellhead. The coupling assembly may include a cylindrical housing having a through hole, the housing adapted to be mounted to the wellhead; a first electrical connector mounted in the housing and having at least one first electrical conductor; a second electrical connector adapted to engage the first electrical connector and having at least one second electrical conductor; and means for sealing the through hole about at least one of the first electrical connector and the at least one electrical connector to substantially prevent the passage of the fluid through the housing. In one aspect, at least one of the first electrical connector and the second electrical connector comprise a plurality of electrodes. In another aspect, the means for sealing the through hole comprises at least one hardenable fluid, for example, an adhesive, such as an epoxy or a silicone.

These and other aspects, features, and advantages of this invention will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention will be readily understood from the following detailed description of aspects of the invention taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevation view of coupling assembly according to one aspect of the invention.

FIG. 2 is a side elevation view of the coupling assembly shown in FIG. 1 partially disassembled to reveal components of the invention.

FIG. 3 is another side elevation view similar to FIG. 2 in which the coupling assembly is completely disassembled to reveal components of the invention.

FIG. 4 is a perspective view of a connector of the coupling assembly shown in FIGS. 1 through 3.

FIG. 5 is a side elevation view of the connector shown in FIG. 4 dissembled to reveal components of the connector.

FIG. 6 is a perspective view of the electrode assembly shown in FIG. 5.

FIG. 7 is another perspective view of the electrode assembly shown in FIG. 5.

FIG. 8 is a side elevational view of the electrode assembly shown in FIGS. 5 through 7.

FIG. 9 is a front perspective view of a female connector according to one aspect of the invention.

FIG. 10 a rear perspective view of the female connector shown in FIG. 9.

DETAILED DESCRIPTION OF ASPECTS OF THE INVENTION

Aspects of the present invention provide novel methods and apparatus that minimize or substantially prevent the passage of harmful gases from well heads, for example, wellheads containing methane or natural gas, while providing at electrical conductors, for example, wires or cables, through the wellhead, for example, to power a pump or other electrical device in the well. One aspect of the invention includes an apparatus for providing at least one electrical conductor to a wellhead containing a fluid while preventing fluid leakage from the wellhead, the apparatus including a cylindrical housing having a through hole, the housing adapted to be mounted to the wellhead, for example, mountable to the mandrel of a wellhead. The apparatus includes at least one electrical conductor, for example, a wire or cable, passing through the hole of the cylindrical housing. The conductor may typically be a coated conductor as is conventional. In one aspect, the one or more conductors may be at least one single, solid wire electrical conductor, that is, a conductor comprising a single solid wire. In contrast to multi-wire cables having multiple twisted strands, single solid wire conductors, for example, single solid copper wire conductors, minimize the number of fluid leakage paths by omitting any interstitial spaces between wire strands that are commonly present in multi-wire conductors. The apparatus also includes means for sealing the through hole in the housing and the at least one electrical conductor to substantially prevent the passage of the fluid through the housing. The sealing means may comprise any material effective to block or fill any flow paths to minimize or prevent leakage of fluids, such as, liquids or gases, for example, methane or natural gas.

Another aspect of the invention is shown in FIG. 1. FIG. 1 illustrates a side elevation view of coupling assembly 10 having a male connector 12 electrically coupled to one or more wires or cables 13 and a female connector 14 electrically coupled to one or more wires or cables 15. Wires 13 typically are electrically coupled to an electrical device, for example, a submersible pump (not shown) positioned in a well shaft, for example, a well shaft having methane or natural gas. Wires 15 typically provide power to the pump, for example, from a panel box or another electrical interface. According to one aspect, male connector 12 may be mounted in a conventional wellhead mandrel (not shown), for example, threaded into a mandrel by means of external threads 16.

FIG. 2 is a side elevation view of coupling assembly 10 shown in FIG. 1 in which connectors 12 and 14 are partially disassembled or disconnected to expose electrodes 18 of connector 12. FIG. 3 is a side elevation view of coupling assembly 10 in which connectors 12 and 14 are completely disassembled or disconnected to expose male electrodes 18 of connector 12 and female electrodes 20 of connector 14. As shown in FIG. 3, connector 14 may be mounted to connector 12 by a plurality of fasteners (not shown) inserted through holes 22 in flange 24 of connector 14 that engage threaded holes 26 in connector 12.

FIG. 4 is a perspective view of connector 12 which includes a housing 28 having internal cavity 29 and electrode assembly 30 having electrodes 18 mounted in internal cavity 29. Housing 28 may be made from a conducting or non-conducting material, but may typically be metallic, for example, a carbon or stainless steel. Electrode assembly 30 is adapted to be inserted into internal cavity 29 and, according to aspects of the invention, housing 28 and electrode assembly 30 are adapted to minimize or prevent leakage of fluids, such as, natural gas or methane, from connector 12, for example, fluids that my be introduced to connector 12 by wires 13 or the interstitial spaces between wires 13. Electrode assembly 30 may have one or more electrodes 18, though four electrodes 18 are shown in FIG. 4. FIG. 5 is a side elevation view of connector 12 with electrode assembly 30 removed from housing 28 to expose wires 13 and the details of electrode assembly 30. FIGS. 6 and 7 are perspective views of electrode assembly 30. FIG. 8 is a side elevation view of electrode assembly 30.

As shown, electrode assembly 30 includes a cylindrical body 32 and electrode mounting plate 34 retaining electrodes 18 and mounted to cylindrical body 32. In one aspect, cylindrical body 32 includes an internal cavity 36 through which wires 13 pass to access electrodes 18. Plate 34 may be mounted to cylindrical body 32 by conventional hardware, for example, by one or more cap screws 35.

Cylindrical body 32 may comprise a dielectric material, for example, a plastic, such as, a polyamide (PA), for example, nylon; a polyamide-imide; a polyethylene (PE); a polypropylene (PP); a polyester (PE); a polytetraflouroethylene (PTFE); an acrylonitrile butadiene styrene (ABS); a polycarbonate (PC); or a vinyl, such as, polyvinylchloride (PVC), DuPont Teflon® PTFE, Saint-Gobain Rulon® PTFE, among other plastics. In one aspect, cylindrical body 32 may comprise a material having a high dielectric coefficient, for example, a polyetherimide (PEI) resin, for instance, GE's Ultem PEI resin, or its equivalent. Plate 34 may be metallic or non-metallic, for example, plate 34 may also comprise a dielectric material, such as one or more of the plastics mentioned above, or an acetal resin, such as DuPont's Delrin acetal resin.

Connector 12 may be adapted to prevent leakage of fluids, such as, natural gas or methane, from housing 28. For example, cylindrical body 32 may include one or more sealing elements 38, for example, one or more o-rings, for example, three (3) o-rings, or similar sealing devices, to minimize or prevent the escape of fluids. Sealing elements 38 may be positioned in recesses (not shown), for example, grooves, in the outside surface of cylindrical body 32, as is conventional. Also, internal cavity 36 may be filled with a fluid leakage minimizing material, for example, one or more rubber gaskets inserted about wires 13; a sealant; and/or an adhesive, for example, an epoxy or a silicone insulation, among other conventional sealing materials.

The ends of wires 13 are electrically coupled to electrodes 18. For example, electrodes 18 may extend through plate 34 and be exposed in internal cavity 36 where the conductors of wires 13 may be soldered to electrodes 18. In one aspect, electrodes 18 may include one or more wire connectors and wires 13 may be connectorized to engage the connectors associated with electrodes 18.

FIG. 9 is a front perspective view of female connector 14 and FIG. 10 is a rear perspective view of female connector 14. In addition to FIGS. 9 and 10, the following description of female connector 14 also makes reference to FIG. 3. As shown, connector 14 includes a housing 40 having an internal cavity (not shown) containing a female connector assembly 42. Housing 40 may be made from a conducting or non-conducting material, but may typically be metallic, for example, a carbon or stainless steel. Female connector assembly 42 is adapted to electrically couple with male connector assembly 30 shown in FIGS. 4-8. Though not shown in FIGS. 3, 9 and 10, connector assembly 42 includes a cylindrical body 44 having holes 45 in which female electrodes 20 are positioned. Electrode assembly 42 may have one or more electrodes 20, though four electrodes 20 are shown in FIG. 9. In a manner similar to electrodes 18 described above, wires 15 are electrically coupled to electrodes 20. For example, wires 15 may be soldered to electrodes 20 or connectorized for engagement with corresponding connectors associated with electrodes 20. Cylindrical body 44 may comprise a dielectric material, for example, one or more of the plastics listed above. In one aspect, cylindrical body 44 may comprise a material having a high dielectric coefficient, for example, a polyetherimide (PEI) resin, for instance, GE's Ultem PEI resin, or its equivalent.

As shown in FIG. 3, housing 40 of connector 14 may include a flange 24 having a plurality of holes 22 through which fasteners (not shown) may be passed to engage threaded holes 26 in housing 28 of connector 12. Housing 40 shown in FIG. 3 includes an expansion from a first diameter into which connector assembly 42 to a second, larger diameter into which wires 15 are inserted. In one aspect, housing 40 may comprise a substantially circular cylindrical housing having no expansion. As also shown in FIG. 3, connector 14 may also include a flange 50 mounted to housing 40 by means of a plurality of fasteners 52, for example, cap screws. According to one aspect, the internal cavity (not shown) of housing 40 may include sealing material (not shown) to seal or protect wires 15, for example, one or more of the adhesives or sealants mentioned above. Flange 50 may be provided to compress the sealing material to seal or protect wires 15 and their connections to electrodes 20.

Connector 14 may be similar to connector 12 and be adapted to prevent leakage of fluids, such as, natural gas or methane, from housing 40, for example, connector 14 include sealing elements such as o-rings. However, in one aspect, since connector 14 may not be exposed to the same pressurized fluids as connector 12, sealing between housing connector assembly 42 and housing 40 my not be necessary. Also, the internal cavity (not shown) of cylindrical body 44 may be filled with fluid leakage minimizing material, for example, one or more rubber gaskets, inserted about wires 15; an epoxy; or silicone insulation, among other conventional sealing materials.

According to aspects of the invention, should a pressurized fluid, for example, natural gas or methane leak into wires 13, for example, into a crack in the casing of wires 13, and pass through wires 13, or pass through interstices between wires 13, unlike the prior art, the fluid will not be allowed to pass through coupling assembly 10. According to the present invention, the isolation of wires 13 from wires 15 prevents any fluids passing through wires 13 to access wires 15 or otherwise pass through housing 28, thus preventing the exposure of any down stream equipment or personnel to noxious or flammable gases, such as, natural gas or methane. In addition, aspects of the present invention provide a convenient disconnection capability that allows maintenance and other service personnel to disconnect the electrical wires leading to a piece of equipment, for example, to a submerged well pump, without requiring the wires to be cut or otherwise damaged.

Though the above figures illustrate a connector assembly 10 having a male connector 12 and a female connector 14, it will be understood by those in the art, that connector 12 may also be female connector and connector 14 may also be a male connector.

While several aspects of the present invention have been described and depicted herein, alternative aspects may be effected by those skilled in the art to accomplish the same objectives. Accordingly, it is intended by the invention comprises all such alternative aspects as fall within the true spirit and scope of the invention. 

1. A method of providing at least one electrical conductor to a wellhead containing a fluid while preventing fluid leakage from the wellhead, the method comprising: providing a cylindrical housing having a through hole, the housing adapted to be mounted to the wellhead; passing at least one electrical conductor through the hole of the cylindrical housing; and sealing the through hole and the at least one electrical conductor to substantially prevent the passage of the fluid through the housing.
 2. The method as recited in claim 1, wherein the fluid comprises at least one of a gas and a liquid.
 3. The method as recited in claim 1, wherein the housing is adapted to be mounted to the wellhead comprises a housing having an external thread engagable with the wellhead.
 4. The method as recited in claim 1, wherein passing at least one electrical conductor comprises passing at least one single, solid wire electrical conductor through the hole.
 5. The method as recited in claim 1, wherein sealing the through hole and the at least one electrical conductor comprises providing a hardenable fluid to the through hole and hardening the hardenable fluid to provide a substantially fluid-tight seal between an inside surface of the through hole and an outside surface of the at least one electrical conductor.
 6. The method as recited in claim 1, wherein the at least one electrical conductor comprises at least one coated single-solid-wire electrical conductor.
 7. The method as recited in claim 1, wherein passing at least one electrical conductor through the hole of the connector comprises passing at least one electrical conductor comprising an electrical coupling.
 8. The method as recited in claim 7, wherein the electrical coupling comprises a first male connector and a second female connector.
 9. An apparatus for providing at least one electrical conductor to a wellhead containing a fluid while preventing fluid leakage from the wellhead, the apparatus comprising: a cylindrical housing having a through hole, the housing adapted to be mounted to the wellhead; at least one electrical conductor passing through the hole of the cylindrical housing; and means for sealing the through hole and the at least one electrical conductor to substantially prevent the passage of the fluid through the housing.
 10. The apparatus as recited in claim 9, wherein the fluid comprises at least one of a gas and a liquid.
 11. The apparatus as recited in claim 9, wherein the housing adapted to be mounted to the wellhead comprises a housing having an external thread adapted to engage the wellhead.
 12. The apparatus as recited in claim 9, wherein the at least one electrical conductor comprises at least one single-solid-wire electrical conductor.
 13. The apparatus as recited in claim 9, wherein the means for sealing the through hole and the at least one electrical conductor comprises a hardenable fluid adapted to provide a substantially fluid-tight seal between an inside surface of the through hole and an outside surface of the at least one electrical conductor when hardened.
 14. The apparatus as recited in claim 9, wherein the at least one electrical conductor comprises at least one coated, single-solid-wire electrical conductor.
 15. The apparatus as recited in claim 9, wherein the at least one electrical conductor comprises an electrical coupling.
 16. The apparatus as recited in claim 15, wherein the electrical coupling comprises a first male connector and a second female connector.
 17. An electrical coupling assembly adapted to provide at least one electrical conductor to a wellhead containing a fluid while preventing fluid leakage from the wellhead, the coupling assembly comprising: a cylindrical housing having a through hole, the housing adapted to be mounted to the wellhead; a first electrical connector mounted in the housing and having at least one first electrical conductor; a second electrical connector adapted to engage the first electrical connector and having at least one second electrical conductor; and means for sealing the through hole about at least one of the first electrical connector and the at least one electrical connector to substantially prevent the passage of the fluid through the housing.
 18. The coupling as recited in claim 17, wherein at least one of the first electrical connector and the second electrical connector comprise a plurality of electrodes.
 19. The coupling as recited in claim 17, wherein the means for sealing the through hole comprises at least one hardenable fluid.
 20. The coupling as recited in claim 19, wherein the hardenable fluid comprises at least one of an adhesive, an epoxy, and a silicone. 